The present invention is directed toward a method of spray coating wires. More particularly, the present invention is directed toward applying a corrosion inhibitor to wires using a low pressure nozzle to achieve a desired spray.
Manufacturers of rubber reinforced articles have long realized the importance of applying corrosion inhibitors to metal reinforcement portions of the article. Corrosion inhibitor coating not only improves the corrosion resistance of the metal reinforcement, but, when the metal reinforcement is present in the form of a cord, the corrosion inhibitor also enables a complete rubber-penetration in towards the central wire of the cord. A complete rubber penetration about the central wire not only improves the resistance of corrosion propagation but also effectively extends the fatigue life expectation of the steel cord.
The corrosion inhibitor is usually present in oil in a preferred percentage by weight and the oil mix is applied to the metal reinforcement. Contacting the oil mix to the cord to be treated is conventionally accomplished by spraying, brushing, doctor blade, dipping, wicking and the like. For example, oil mixtures can be applied by dipping the cord into the oil mix and using a mechanical or air wipe to control the desired amount of chemical mix on the cord. The oil mix can also be applied by wicking or rubbing the cord against a material that transfers the oil mix. This procedure is subject to variable concentration on the cord.
The application processes can be incorporated after the cabling of the wire but preferably the oil mix is applied to the wire filaments during the cabling, bunching or spiral wrapping process. In addition, the oil mix can be applied just before a rubber/steel cord calendering operation. The calendering operation is the step when the treated cord is embedded between two layers of the rubber and pressed to form the metallic reinforced rubber ply. The calendering step is well known to those skilled in the art.
In order to apply corrosion inhibitor technology in the wire processing line or in the tire production line, a well-defined corrosion inhibitor coating process is needed.
In the present invention, a spray coating process combines an oil mix spray unit with a low air pressure nozzle to deliver minute quantities of ultra-fine spray of corrosion inhibitor onto a wire surface during a wire processing step. Using the low air pressure nozzle, corrosion inhibitor can be sprayed at a pressure less than one pound per square inch. This system enables an accurate, clean delivery of corrosion inhibitor fluids to the steel cord surface without environmental contamination.
Disclosed is a method of coating a wire with a corrosion inhibitor. The method employs the steps of passing a wire over a pulley and applying a spray of an oil mixture onto the wire. The oil mixture contains at least the desired corrosion inhibitor. To form the ultra-fine spray, the spray is applied at an air pressure in the range of less than 1 to 15 psi.
In a further aspect of the invention, the ultra-fine spray applied to the wire is formed of oil mixture droplets having a maximum diameter of 10xe2x88x925 to 10xe2x88x924 meters.
In another aspect of the invention, the oil mixture is applied by bringing together an oil mixture feed line, supplied at a pressure of 50 to 100 psi, and an air feed line, supplied at a pressure of less than 1 to 15 psi.
In another aspect of the disclosed method, the wire is passed about a pair of pulleys. Each pulley has an associated low pressure spray nozzle.
In another aspect of the disclosed method, the wire passes through a groove in the pulley. Coating of the portion of the wire adjacent the pulley groove with the corrosion inhibitor is aided by any oil mixture present in the pulley groove.
Cord: means one or more of a reinforcing element, formed by one or more filaments or wires which may or may not be twisted or otherwise formed. Therefore, cords may comprise from one (monofilament) to multiple filaments. The number of total filaments or wires in the cord may range from 1 to 134. Preferably, the number of filaments or wires per cord ranges from 1 to 49.
Cord Constructions: means a winding arrangement of a number of filaments or wires to form a cord. The number of cord constructions which can be treated according to the present invention are numerous. Representative examples of such cord constructions include 2xc3x97, 3xc3x97, 4xc3x97, 5xc3x97, 6xc3x97, 7xc3x97, 8xc3x97, 11xc3x97, 12xc3x97, 27xc3x97, 1+2, 1+3, 1+4, 1+5, 1+6, 1+7, 1+8, 1+14, 1+15, 1+16, 1+17, 1+18, 1+19, 1+20, 1+26, 2+1, 2+2, 2+5, 2+6, 2+7, 2+8, 2+9, 2+10, 2/2, 2/3, 2/4, 2/5, 2/6, 3+1, 3+2, 3+3, 3+4, 3xc3x974, 3+6, 3xc3x977, 3+9, 3/9, 3+9+15, 4+3, 4xc3x974, 5/8/14, 7xc3x972, 7xc3x973, 7xc3x974, 7xc3x977, 7xc3x9712, 7xc3x97l9, 5+1, 6+1, 7+1, 8+1, 11+1, 12+1, 2+7+1, 1+4+1, 1+5+1, 1+6+1, 1+7+1, 1+8+1, 1+14+1, 1+15+1, 1+16+1, 1+17+1, 1+18+1, 1+19+1, 1+20+1, 2+2+8, 2+6+1, 2+7+1, 2+8+1, 2+9+1, 2+10+1, 2+2+8+1, 3+9+15+1, 27+1, 1+26+1, 7xc3x972+1, 3+9+1, 3/9+1, 7xc3x9712+1 and 7xc3x9719+1. The filaments in the cord constructions may be preformed, waved or crimped. The preferred cord constructions include 2xc3x97, 3xc3x97, 1+5, 1+6, 1+18, 2+7, 3+2, 3+3 and 3/9+1.
Metallic cord: means a steel, zinc-plated steel or brass-plated steel cord.
Oil Mix: means a oil containing a corrosion inhibitor. The oil mix has a kinematic viscosity of 460-9200 cSt (460-9200 mm2/s) at room temperature.
Steel: means a steel substrate derived from conventional processes known to those skilled in the art. For example, the steel used for wire may be conventional tire cord rod including AISI grades 1070, 1080, 1090 and 1095. The steel may additionally contain varying levels of carbon and microalloying elements such as Cr, B, Ni and Co.
Wire Diameter: means the diameter of an individual wire or filament that is encapsulated or used in a cord. For steel cords used in manufacturing tires, the wire diameter may range from about 0.08 to 0.5 mm. Preferably, the diameter ranges from 0.15 to 0.42 mm.